Theresa May said Labour's anti-Semitism crisis 'sickened' her at a speech for the United Jewish Israel Dinner

And in direct reference to Labour’s defence of its record, she stormed: “You cannot claim to be tackling racism, if you are not tackling anti-Semitism.”

She added: “Nothing excuses anti-Semitism – not comedy, not satire, not even irony.” Jeremy Corbyn was slammed last month over remarks in 2013 when he said British Zionists don’t understand “English irony”.

Speaking at the United Jewish Israel Dinner, the PM didn’t mention Jeremy Corbyn or Labour by name. But it marks her biggest attack on the Labour leader yet over the crisis that engulfed the Opposition all summer.

Four in ten British Jews said they may leave the country if Jeremy Corbyn wins the next election

Mr Corbyn incensed the Jewish community at a summit earlier this month by claiming activists should be able to call Israel’s existence “racist”.

He had been seeking to dilute the international IHRA definition of anti-Semitism which was finally accepted by the party’s ruling NEC committee – with a freedom of expression caveat.

Speaking last night the PM insisted the “scourge of anti-Semitism” would be defeated. And she said a poll by the Jewish Chronicle – claiming four in ten British Jews may leave the country if Jeremy Corbyn became PM – almost defied belief.

She said: “It sickens me that anyone should feel like that in our country.

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